Relief device for lubricating systems



June 30, 1953 H. R. TEAR 2,643,739

RELIEF DEVICE FOR LUBRICATING SYSTEMS l Filed July 1s, 1949 Patented June 30, 1953 RELIEF DEVICE FOR LUBRICATING SYSTEMS Harry R. Tear, Evanston, Ill., assigner to Stewart- Warner Corporation, Chicago, Ill., a corporation of Virginia Application July 13, 1949, Serial No. 104,544

The present invention relates generally to lubricating systems andmore particularly to an automatically operating valve for relieving the pressure in a lubricating system inthe intervals between the application of fluid under pressure to the system.

' An object of the invention is to provide a new and improved pressure relief device which operates automatically to relieve the pressure on the inlet end of the line in a lubricating system through a bypass around the pump of the system When the application of lubricant under pressure to the line ceases.

Another object of the invention is to provide a new and improved lubricating system having a valve-controlled bypass" means for the inlet end of the line which closes automatically upon the application of lubricant under pressure to the line, and whichy opens automatically to relieve vset forth in the foregoing objects which is eX- ceedingly simple in construction, may be economically manufactured, and which will operate satisfactorily under widely varying conditions of operation.

These and other objects, advantages, and capabilities of the invention will become apparent from the following-description, in which reference is had to the accompanying drawings, wherel Fig. 1 is a diagrammatic view of a fragment of `a lubricating system showing the improved pressure relieving means for the system installed therein; and

Fig. 2 is a sectional View through the'improved pressure relieving means of the present invention.

In the diagrammatically illustrated portion of a single line lubricating system, shown in Fig, 1, a fragment oi a source of lubricant supply, which may be a drum or other container, is indicated f at i6. Lubricant is drawny from this source by a pump l2 and deliveredvunder pressure to an outlet conduit le which is connected to the inlet end of the improved pressure relief device indicated in its ,entirety by the number I6. This 4 Claims. (Cl. 184-7) relief device has an outlet connected to the inlet end of a conduit or line 20 forming part of a single line lubricating system. f

Only representative parts of this system are shown in Fig'. 1, but such systems conventionally include a plurality of measuring devices 22 interconnected by the conduit 20 and each associated with a bearing to be supplied with lubricant. Upon the application of iiuid under pressure to the line, the measuring devices progressively discharge vmeasured charges of lubricant to `the bearings with which they areassociated. After all the measuring devices have operated, operation or" the pump l2 is discontinued by automatic controls, or by manually operated means. Structure for accomplishing this is `known and is, therefore, not herein shown or described in detail. It will be understood that the measuring valves in a system are associated with a group of bearings for one machine, orgroup of machines.

The pump I2 may be of any known suitable I the piston rod for operating the .piston in the pumping cylinder. It mayA also form an .outlet passageway for lubricant from the pump` cylinder to the outletr of the pump. Since pumpsof various types available on the market may be used, a detailed description of the pump is unneces- Referring to Fig. 2, it will be seen that the pressure'relief device It includes an elongated body member which has a longitudinally extending duct or passageway 32 formed therein and has a' threaded inlet end 34 adapted to'bedetachably connected to the outlet conduit lll leading from the pump by suitable coupling means 3S. A threaded outlet 3l for the passageway 32 is connected to the end of the line 26 by coupling means 38. 'f

Intermediate the inlet and outlet ends of passageway 32 there is a bail check valve il to prevent return flow of lubricant from thev'line to the inlet side of passageway 32a. A spring 42 reacting between a bushing press-fitted in the outlet end `of the passageway biases the'valve toward a valve seat i6 v:formed in the passageway, but the pump I2 develops suiiicient pressure to maintain the valve 48 open while the pump is operating. However, when` the pump I2 stops operating spring 42 closes check valve 48, thus trapping the lubricant on the outlet side of the check valve so that the pressure in the line 28 remainsgat some'relatively high value. 'Ihepresent invention includes novel means for relieving this pressure.

This novel means includes a valve casing 48-` which may be secured to the tubular body member 30 by threading its inner end 58' into an aperture B in the tubular body member S communicating radially with thepassagewayf 32: on the inlet side of check valve 48; The valve casing has a, cylindrical bore 52, the inner end of which communicates with the passageway 32 on theY inlet side of check valve 40 through an apertured plug or bushing 54 press-fitted in theY end ofV bore 52 and also held in position by deforming inwardly the threaded end of the valve casing 48.

The opposite end of the valve casing 48 communicatesA with the side of the passageway 32 on'the outlet side ofthe check valve 4Il-through a, pressure relief channel or conduit 58 secured Vat one endY to the valve casing and at the other endito` a suitable connection iitting GII threaded into. a; tappedl bore intersectingv the passageway 321 radiallyv on the outlet side of the check valve 4I).

AY similar connection. is made between the Aother endv ofy the conduit 58 and the valve casing 48. In this case, however,l the connection includes. a iitting 62, which is threaded into the enlargedouterend of the bore 52 in the valve casing, and has abore 64 of reduced diameter, and; an enlargedy bore` 66 which communicates with the; interior of the valve casing 48.

Valvevcasing 48 has avent 68, which may be r connected to a return pipe or conduit 78, dis,- charging freely into container I8. Communication between the passageway 32 in the tubular body member 30 and the vent 68 is controlled by a hydraulic operatory in the form of a pistonvalve 'I2' which has a head or piston 'I4 slidable in the bore 52. Piston 'I4 has slight clearance in the bore 52 permitting constant but minute leakage of lubricant from theA bushing 54 to-the vent (i8 while there is pressure onthe inlet side to' be described.

In Fig. 2 the relief valve is shown in the position it assumes when the pump is not operating, at which time both ends of the passageway 32 are at substantially atmospheric pressure. When the pump I-2 resumes operation, the pressure on the inlet side of passageway 32 exceeds that on the outlet side 31 due to the pressure drop across the loaded check valve 48. This pressure is transmitted to the valve chamber 48 through bushing 54 and acts on the piston 'i4 causing the valve member 'I2 to move to the right until the ball valve 'I8 engages upon the seat 84. Since the leakage past the piston I4 is minute compared with the discharge of the pump, the

check valve 48 will be maintained open while the pump is operating and the valve I8 will remain seated to cut off communication between the outlet side of the passageway 32 and the vent 68 thus preventing bypassing of lubricant from the system while the pump continues to operate.- f

Thisl condition,Ik will prevail until operation of the pump I2 is discontinued. Thereupon the check valve 40 closes and the pressure in passageway 32 onthe inlet side of this valve is relieved by leakage of lubricant past the piston 'I4 and to the vent 68 while that on the outlet side remainsthe same for the time being because the relatively large area of the piston 'I4 subject to the pressure onthe inlet side of passageway 32 compared with` the small area of the ball valve T8 subject to the pressure in the outlet side of passageway 32 results in the ball valve 'I8 being held seated. However, when the pressure in the inletv side of passageway 32k falls to somefraction of that in the outlet side thereof, the valve member 'i2 will be moved in a direction to unseat ball valve 'I8 by the pressure of lubricant onthe outlet side of check valve 40; This pressure is transmitted to the ball valve 'I8 throughv tting 68, conduit 58, and bore 64 in tting 62'. Communication between the line 28 and the vent BB is thus established so that back pressure in the line is relieved.

From the above description of the construction and operation of the invention, it will be apparent that a device of exceedingly simple construction has been provided, Whichnevertheless is positive in its operation, and hasfew parts to get out oforder. This device operates automatically and in response to the application of lubricant under pressure to the line to close the bypass from the line, and to open the bypass when the application of pressure tothe line ceases.

While I have shown and described a preferred embodiment of my invention, it will be apparent that, numerous variations and modiiications thereof may be made without departing from the underlying principles of the invention. I therefore desire, by the following claims, to. include within the scope of the invention all such variations and modications by which substantially the` results of my invention may be obtained through the use of .substantially the same or equivalent means.

I claim:

l. A device for relieving pressure in a fluid.- conveying line when the application ofY fluidV under pressure to the line ceases, comprising a body adapted to be interposed between the source of fluid and the line and having a duct extending through the same and a check valve in the duct, means forming a passagewayv having communication with the duct in said body on opposite sides of said check valve including a vent and a port between said vent and the outlet side of said check valve, and a diierential valve slidable in a portion of said passageway including a head slidable in the said portionof said passageway between the inlet side of the check valve and the vent having` slight clearance with the said portion of said passageway to allow minute leakage between the inlet side of said duct and said vent for relieving the pressure in the inlet side of said duct when said check valve closes, and a part to closeV said port when said diiferential valve moves in response to a greater pressure on the inlet side of the check valve than on the outlet side thereof, said port being of small cross-sectional area relative to the head of said differential valve so that the latter will move in a direction to open said port only when the pressure on the outlet side of the check valve exceeds that on the inlet side by a predetermined amount.

2. A pressure relief device adapted to be interposed between a source of lubricant under pressure and the lubricant-conveying line of a lubricating system, comprising a vbody having -a passage therethrough with an outlet end adapted to be connected to said line and an inlet end adapted to be connected to said source of lubricant, a check valve between said inlet and outlet, means forming a Valve chamber having a cylindrical bore, a vent for said chamber, means for establishing communication between the inlet side of said passage and one end of said bore, other means for establishing communication between the outlet side of the passage and the other end of said bore including a relatively small port in the valve chamber, and means for controlling communication through the port including a valve having a piston slidable in said bore between the end thereof connected to the inlet side of the passage and the vent in response to a pressure differential across the passage, and a part adapted to close said port when the valve moves in response to a greater pressure at the inlet than the outlet side of said passage, said piston having sucient clearance in said bore to allow slight leakage between the inlet side of said -passage and said vent for relieving pressure in the said inlet side when the check valve closes, said port being of small cross-sectional area relative to said piston so that a pressure must exist in the outlet side of the passage exceeding the pressure on the inlet side by a predetermined amount before the valve will move in a direction to open the port.

3. In a lubricating system, an intermittently operated pump having means forming an outlet passageway, a check valve in said passageway for preventing return flow of lubricant to the pump, means forming a pressure relief channel for the iiow of lubricant from the outlet end of the outlet passageway to a low pressure space, a poppet type valve of relatively small diameter operable to close said channel, means forming a cylinder of diameter substantially greater than that of the poppet valve and having one end in communication with the inlet end of said outlet passageway and having its other end in communication with a low pressure space, a piston freely slidable in the cylinder, and an operative connection between the piston and the poppet valve to hold the latter closed during the time that the pump is operating to maintain a substantial pressure at the inlet end ofthe outlet passageway.

4. In a lubricating system, an intermittently operated pump, means connected to the outlet of the pump and forming an outlet passageway, a check valve in said passageway for preventing return flow of lubricant to the pump, means forming a pressure relief channel for the ow of lubricant from the outlet end of the outlet passageway to a low pressure space, a poppet valve of relatively small diameter operable to close said channel, a hydraulic operator including a chamber having a movable wall of effective area substantially greater than that of the poppet valve, means connecting the chamber with the inlet end of said outlet passageway, said hydraulic operator being formed to provide a minute passage for leakage of lubricant from the chamber to the low pressure space, and an operative connection between the movable Wall of the hydraulic operator and the poppet valve to hold the latter closed during the time that the pump is operating to maintain a substantial pressure at the inlet end of the outlet passageway.

HARRY R. TEAR.

References Cited in the file 0f this patent UNITED STATES PATENTS Number 

